Recreating the problem will probably be a bit convoluted, but should
be possible. Things are also complicated by the fact that I'm using
the current developers' version of petsc. I am presently getting
around the problem by reverting to an older version of g95, but I
believe that this is a symptom of the problem rather than the cause.
The primary differences between the two versions is that the newer
one does not include libgcc_s.dylib. Anyway, assuming you have
access to a Tiger system, here is how you should be able to recreate
the situation:

1. Install the current fink version of g95 (0.50-20051002).

2. Configure and build Open MPI after setting FC and F77 to g95.

3. Get the current developers' version of PETSc. I believe there is
a tarball version available at ftp.mcs.anl.gov/pub/petsc. They used
to hide it by putting a dot in front of the name, but I just looked
and that no longer seems to be the case. I am instead using the open-
source BitKeeper client to grab things. You will need to get both
the main package (bk://petsc.bkbits.net/petsc-dev) as well as the
BuildSystem package (bk://sidl.bkbits.net/BuildSystem), which should
be installed in ${PETSC_DIR}/python/BuildSystem.

4. This is where things get a little tricky. So far, I have to edit
a couple of the PETSc files to get things working properly with Open
MPI. Open MPI appears to build two-level namespace libraries on OSX
by default, where PETSc attempts to build the old-style flat
namespace libraries. I haven't been able to get shared and dynamic
libraries to build properly using their default setup with Open MPI.
The two files in question are ${PETSC_DIR}/bmake/common/
rules.shared.basic and ${PETSC_DIR}/python/BuildSystem/config/
setCompilers.py. I have attached edited copies of both files. If
you want to build the python bindings using Open MPI, you also need
to edit a third file (${PETSC_DIR}/python/config/base.py), which I
have also attached.